Foot-length caliper for measurement of foot length and screening of birth weight groups

ABSTRACT

A caliper to measure foot length and corresponding category of birth weight group by four colors used on the measuring scale namely. Green as normal, yellow as low, orange as very low and red as extremely low birth weight is devised for the first time to be used at the community level. A metal caliper with concavity to accommodate convexity of the heel and sliding device perpendicular to the scale to touch the longest toe fix the two extreme ends. Thus direct measurement is possible between two extreme ends of the foot.

BACKGROUND OF THE INVENTION

The present invention relates to medical science and, more particularly, to the field of pediatrics wherein a foot length caliper is devised which will measure the length of a foot from the heel of the foot to the tip of the big toe of the foot.

The caliper according to a preferred embodiment of the present invention is useful for screening of a baby into grades of birth weights. Examples of such weight grades are <1500 grams, 1500 to 1999 grams, 2000-2499 grams, and above 2500 grams.

Birth weight of a baby is one of the most important parameters to judge the growth of the fetus in the uterus and is related to survival of the baby in the neonatal period. By knowing the birth weight, the baby can be categorized into different weight groups. The strategies for care and referral of the baby differ with the birth weight of the baby. Babies having a weight below 1500 grams generally need intensive care in neonatal intensive care unit at hospital. Babies having a weight between 1500 to 1999 grams can generally be cared for at a primary health center, first referral unit, rural hospital or community health center. Babies having a weight between 2000-2500 grams can generally be cared for at home, with occasional home visits of health auxiliaries and training of the mother.

At present, about 60 to 70% of the deliveries in rural areas take place in primary health centers or hospitals with facilities for weighing of the baby. In the case of deliveries which take place at home, very often the health worker can reach the place of delivery only after the information about delivery is obtained by the health worker. The birth weight measurement, however, is valid only if it is taken within twenty four hours of birth.

Foot length is known to be associated with birth weight and can be used as a proxy for birth weight. Foot length is not affected by a time lapse of a couple of days as with the birth weight of a baby. Thus, foot length can be considered as a good alternative for weighing of babies at birth for home deliveries.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, in one embodiment, the present invention is directed to a caliper for measuring a length of a foot. The caliper comprises a concave portion configured to accommodate a heel of the foot, a measurement scale, and a slider which slides in a direction perpendicular to a direction of extension of the scale. The scale is divided into a plurality of zones, each of the zones corresponding to a category of birth weight.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings an embodiment which is presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

In the drawings:

FIG. 1 is a top plan view of a caliper in accordance with a preferred embodiment of the present invention.; and

FIG. 2 is a top plan view of a caliper in accordance with another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a calliper, preferably a metal calliper, designed so that the convexity of a heel of a foot can be rested in or on a concave portion of the calliper device. Referring to FIG. 1, the foot length calliper 20 consists of two parts, namely main body 1 and the slider 2. The main body 1 at the bottom is provided with a semi-circular and concave heel support/stopper portion 4. The slider 2 slides freely on the main body 1. The slider 2 is so designed that the upper edge, which is the reading edge 8, of the slider remains perpendicular to the edge of the main body 1. The main body 1 is fitted with a scale 3, preferably in centimetres or inches. The slider 2 has a lip 6 at the lower edge, which is parallel to the reading edge 8. The lip 6 protrudes perpendicularly out from the slider 2.

The zero point of the scale is moved upwards by the distance equal to the distance between the lip 6 and the reading edge 8. This ensures that the distance between the lowest point on the main body 1 and the lip 6 is correctly indicated by the reading edge 8. Accurate measurements of length are possible between the lowermost part of the heel and the uppermost part of the toe. Since this measurement is an actual objective measurement, there is no inter-personal variation.

As shown in FIG. 2, in one embodiment, the scale 3 on the main body 1 of a calliper 20′ is preferably coded to indicate different measurement zones. Preferably, four zones are demarked on the scale 3 using four different colors. More preferably, the scale 3 provided with four color coded zones, where, for example, a first zone 22 is coded green and represents a normal birth weight category, a second zone 24 is coded yellow and represents a low birth weight category, a third zone 26 is coded orange and represents a very low birth weight category, and a fourth zone 28 is coded red and represents an extremely low birth weight category.

Preferably, the first green zone 22 is demarked on the area of the scale 3 above the 7.8 cm marker line, indicative of birth weight of 2500 grams and above; i.e., a normal birth weight. Preferably, the second yellow zone 24 is demarked on the area of the scale 3 between the marker lines for foot lengths of 7.4 cm up to 7.8 cm, and indicates a birth weight group of 2000 grams up to 2500 grams; i.e., low birth weight. Preferably, the third orange zone 26 is demarked on the area of the scale 3 between the marker lines for foot lengths of 7.4 cm and 6.5 cm, and indicates a birth weight group of 1500 grams up to 2000 grams; i.e., a very low birth weight. Preferably, the fourth red zone is demarked on the area of the scale 3 below the marker line for a foot length of 6.5 cm, and indicates a birth weight below 1500 grams, which is an extremely low birth weight. If the color coding is ignored, the same calliper can be used for measuring foot length correctly of the baby until the baby's foot length is 10 centimetres.

The main body 1 is also preferably provided with a hole 12 at the top and a dimple 5. The dimple 5 acts as a stopper for the slider 2 and does not allow the slider 2 to slip out of the main body 1. The hole 12 is provided for placement of the calliper on a wall when not in use.

There could be observer error in measuring foot length when measured by a conventional measuring tape. Also, impressions of a foot with ink can vary depending upon the pressure applied to the peripheral areas of the foot, resulting in variation in length readings of the same foot. The calliper according to preferred embodiments of the present invention is able to fix the two extreme ends of the foot and measure the distance between these two extreme ends, namely between the lowermost point on convex curvature of the heel and the uppermost point on the convex curvature of the toe.

The calliper is preferably used as follows:

While taking a measurement, the baby's foot is positioned in such a way that the convexity of the baby's heel is rested at lowest point of the heel support/stopper 4, snugly within the concavity of the calliper. The slider 2 is then brought down towards the foot until the lip 6 of the slider 2 just touches the highest point of the baby's toe, without exerting any pressure on the toe. That is, the slider 2 can be brought exactly at the upper most point on the convex curvature of the baby's toe. The foot length reading will be given at the upper edge of the slider 2; that is, the reading edge 8. This indicates the accurate length of the baby's foot, preferably within at least one millimetre accuracy.

In one embodiment, the zone of the scale 3 in which the measurement falls indicate birth weight group as shown in Table 1.

TABLE 1 Corresponding Foot length Birth Weight Zone Color (cm) (grams) Analysis 1 Green >7.8 cm ≧2500 gm Normal birth weight 2 Yellow Between 7.4 2000 to <2500 Low birth weight and 7.8 cm gm 3 Orange Between 6.5 1500 gm Very low birth and 7.4 cm to <2000 gm weight 4 Red Below 6.5 Below 1500 Extremely low birth cm gm weight

Depending on the zone of birth weight indicated by the measurement, interventions at a peripheral level can be undertaken by the health workers without memorizing the foot length and birth weights for a particular category, avoiding confusion of cut off points and simplifying referral and care at the peripheral level. The monitoring of the foot length can preferably be continued after birth, until the baby's foot reaches 10 cm, ignoring the color coding of the scale 3.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims. 

I claim:
 1. A caliper for measuring a length of a foot comprising a concave portion configured to accommodate a heel of the foot, a measurement scale, and a slider which slides in a direction perpendicular to a direction of extension of the scale, wherein the scale is divided into a plurality of zones, each of the zones corresponding to a category of birth weight.
 2. The caliper according to claim 1, wherein the zones are color coded zones.
 3. The caliper according to claim 2, wherein a green zone corresponds to a normal birth weight, a yellow zone corresponds to a below normal birth weight, an orange zone corresponds to a birth weight lower than that of the yellow zone, and a red zone corresponds to a birth weight lower than that of the orange zone. 